{"id":272,"date":"2024-02-09T10:11:24","date_gmt":"2024-02-09T10:11:24","guid":{"rendered":"http:\/\/maddox.pro\/?p=272"},"modified":"2024-02-09T10:11:24","modified_gmt":"2024-02-09T10:11:24","slug":"pdp11-hack-bus-display","status":"publish","type":"post","link":"https:\/\/www.maddox.pro\/?p=272","title":{"rendered":"PDP11 Hack+ Bus display"},"content":{"rendered":"\n<p>Well I got the PCB and assembled it, and first off when I powered the board up it caused my PSU to go into over current protection. After a little investigation I realised I had grounded the left and right dots, which are not logic inputs like the rest of the chip for some reason, they are the cathodes of the LEDs. So I was basically putting a whole bunch of LEDs between 5V and 0V, oops. So having fixed that, it does indeed light up.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"661\" height=\"1024\" src=\"https:\/\/www.maddox.pro\/wp-content\/uploads\/2024\/02\/IMG_6149_crop-661x1024.jpg\" alt=\"\" class=\"wp-image-273\" srcset=\"https:\/\/www.maddox.pro\/wp-content\/uploads\/2024\/02\/IMG_6149_crop-661x1024.jpg 661w, https:\/\/www.maddox.pro\/wp-content\/uploads\/2024\/02\/IMG_6149_crop-194x300.jpg 194w, https:\/\/www.maddox.pro\/wp-content\/uploads\/2024\/02\/IMG_6149_crop-768x1190.jpg 768w, https:\/\/www.maddox.pro\/wp-content\/uploads\/2024\/02\/IMG_6149_crop-991x1536.jpg 991w, https:\/\/www.maddox.pro\/wp-content\/uploads\/2024\/02\/IMG_6149_crop-1322x2048.jpg 1322w, https:\/\/www.maddox.pro\/wp-content\/uploads\/2024\/02\/IMG_6149_crop-1140x1766.jpg 1140w, https:\/\/www.maddox.pro\/wp-content\/uploads\/2024\/02\/IMG_6149_crop-scaled.jpg 1652w\" sizes=\"auto, (max-width: 661px) 100vw, 661px\" \/><\/figure>\n<\/div>\n\n\n<p>The next problem is that I forgot to include the enable line for the memory so that it only displays memory data\/addresses rather than anything, which means that as the serial port is mapped as a device with an address range of 17777560-17777566 you pretty much only ever see that.<\/p>\n\n\n\n<p>So a 2nd revision of the PCB is needed, a fix for the dot issue and a fix for the memory decoding issue.<br>In addition this board pulls around 1.2A and the displays get toasty warm, so I will also add a simple oscillator to change the brightness and also reduce the current\/heat from the displays.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Well I got the PCB and assembled it, and first off when I powered the board up it caused my PSU to go into over current protection. After a little investigation I realised I had grounded the left and right dots, which are not logic inputs like the rest of the chip for some reason, they are the cathodes of the LEDs. So I was basically putting a whole bunch of LEDs between 5V and 0V, oops. So having fixed that, it does indeed light up. The next problem is that I forgot to include the enable line for the memory so that it only displays memory data\/addresses rather than anything, which means that as the serial port is mapped as a device with an address range of 17777560-17777566 you pretty much only ever see that. So a 2nd revision of the PCB is needed, a fix for the dot issue and a fix for the memory decoding issue.In addition this board pulls around 1.2A and the displays get toasty warm, so I will also add a simple oscillator to change the brightness and also reduce the current\/heat from the displays.<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[25],"tags":[32,26,28,31],"class_list":["post-272","post","type-post","status-publish","format-standard","hentry","category-pdp11hackplus","tag-dcj11","tag-pdp11","tag-pdp11-hack","tag-retro-computer"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.maddox.pro\/index.php?rest_route=\/wp\/v2\/posts\/272","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.maddox.pro\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.maddox.pro\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.maddox.pro\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.maddox.pro\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=272"}],"version-history":[{"count":1,"href":"https:\/\/www.maddox.pro\/index.php?rest_route=\/wp\/v2\/posts\/272\/revisions"}],"predecessor-version":[{"id":274,"href":"https:\/\/www.maddox.pro\/index.php?rest_route=\/wp\/v2\/posts\/272\/revisions\/274"}],"wp:attachment":[{"href":"https:\/\/www.maddox.pro\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=272"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.maddox.pro\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=272"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.maddox.pro\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=272"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}